When you sit inside an enclosed place (like a car, a small room, etc.) and smoke up. You will breathe in the smoke in the air, as well as through whatever your smoking out of. Once you get out of the place into fresh air, it hits you real hard and you become really high. Same thing as clam baking.

getting into a car, rolling up the windows and getting high. The whole purpose of this event is to celebrate manhood by lighting up joints in a closed car, therefore inhaling more of that pure weed smoke.